1. Field of Invention
The present invention relates to setting the charge rate in a wireless pay phone.
2. Description of the Related Art
Today it is becoming increasingly common to use wireless pay phones in various vehicles, such as trains, boats or buses. It becomes difficult to set the charge rate of calls or other services if a vehicle in which a pay phone is located travels over a broad area, for example, in several different countries or, more generally, in several areas that affect charge rates, which are specified by call tariffing. The originating zone of a call made with a roaming wireless pay phone may also change from time to time, which should also be taken into consideration in setting the charge rate. A user naturally expects the pay phone charge rate to be similar to that of his or her own mobile phone for a given call or service. A provider of a pay phone service also benefits if the ratio between the pay phone charge rate and the actual charge rate of a call or service is always nearly the same or at least under the control of the provider.
No reliable and flexible solution currently exists for setting the charge rate in a wireless pay phone that takes into account the originating zone and destination zone of a call. Until now, the charge rate has been primarily set based on the selected phone number or service number. It has also been possible to take a pay card used to operate a pay phone into account in setting the charge rate. For wireless phones where the originating zone of a call does not change and the operator is therefore always the same, the charge rate may be set by using a net tariffing service, such as AoC (Advice of Charge) for GSM phones and Q1Q2 for NMT phones. However, it is difficult to use a net tariffing service if a pay phone roams and the net and operator changes, because uninterrupted availability and reliability of the service cannot be guaranteed.
The charge rate of a roaming pay phone has been set by loading a charge rate table into the phone. The charge rate table is based on either the charge rate of the predominant call originating zone or an average charge rate of the area in which the vehicle travels. In order to ensure that the right charge rates are applied, a new charge rate table should be loaded into the pay phone each time it enters an area with different tariffing for calls originating in that area, which may be a different country. The provider of the service should replace the table, and this in itself is difficult to arrange. It has been suggested that a new charge rate table could be loaded by means of a radio interface using a short message service or a modem. The quantity of information may be from a few kilobytes to 10 kilobytes, which would require a considerable amount of time to transfer. For example, 10 kilobytes is equivalent to 100 messages in a typical short message service, which would require at least 6 minutes to send. At least one minute of air time would be needed to send this information by modem. If it is arranged so that a new table is loaded in conjunction with certain handovers, this would result in a considerable number of extra data transfers, because handovers occur often in a moving vehicle.